I think this is probably exaggerated. IN windows basically all old softwware works with very little fiddling. Maybe downloading a dll it literally just tells you it needs, maybe trying a few different compatibility modes. It is normally a <5 minute affair.
I am glad that MS goes ahead and fixed some of the most popular software, but even the ones they clearly did not do this for, work almost as seamlessly.
There have been some notable application-specific hacks applied, at least in previous generations of Windows. SimCity comes to mind: it used memory after free and Windows... 95(?) broke it, so a hack was put in place to explicitly allow processes named simcity.exe to use memory after free. Or something like that.
What people miss from the story is why it was so important that Microsoft do that (and it's a similar reason to why Linus insists on never breaking userspace).
I am glad that MS goes ahead and fixed some of the most popular software, but even the ones they clearly did not do this for, work almost as seamlessly.